Continuity mistake: Benoit Blanc tells his partner to get the door and unconvincingly says he is not in the bath, his left-hand changes blatantly position between shots. Throughout the whole scene in fact you can see Daniel Craig's hand by the second laptop in the side views but not on the close-up of the remote call. (00:12:25)
Continuity mistake: When the Disruptors flick the final switch, Lionel's finger in the split screen shot comes from the right side of the frame, where the "7" is. In the shot of his desk though he is positioned on the opposite side of the box. (00:09:10)
Continuity mistake: The friends crack the final puzzle of the box and it open. Look at Lionel's desk when that happens; the shadows and the distance between the box itself and the crazy fax papers ("Nootrodic Nasal Spray"?) change between shots. (00:09:15)
Continuity mistake: When Claire calls Lionel at 14:07 asking him about the puzzle box, the phone in close-up is in a spot far away from any edge, while in the wider angle it's practically on the edge. (00:04:00)
Continuity mistake: An odd creepy guy ("Vampire in a tuxedo" according to the credits) gives Birdie an approving nod when she protests against the "woke" people that don't let her racial slur slide. She says "Love you, yes!" pointing at him, with the elbow of the other arm fully lying on the lap of the girl on the couch. Next shot and her pose changed entirely, no physical contact with other guests. (00:03:50)
Continuity mistake: The very first shot with Kate Hudson ends with her shouting for her assistant Peg. Look at the position of her fingers on the glass, very close to the rim. She is still shouting in the reverse angle but her grip on the glass changed. (00:03:05)
Character mistake: During the dénouement, Benoit Blanc starts "That night, Lionel faxed Andi's email to Miles." But it's established that he faxed it minutes after receiving the mail, which was sent at 4 pm. 4 pm in May, that's hardly 'night'. And it can't be night where Lionel is, since he shows up a little later together with Claire, from Connecticut, at the house of the victim in the New York area. (01:52:25)
Continuity mistake: Miles tries to rally the troops after Helen delivered the line about him being ruined. He calls out "Gang?" Lionel is staring into space facing away from him, then in close-up he is still staring into space, but turned more towards him. (02:09:40)
Audio problem: Helen reminds Miles the line he used "To forever be remembered in the same breath as the Mona Lisa." The line is said in the span of a couple different angles; when she says the word "in the same", the camera is behind her, and you can see that her jaw is not moving. (02:09:15)
Continuity mistake: The bloodstains on Helen's top change midway through the ending. For instance, when she walks towards Miles after smashing most of the glass sculptures to eventually show him her trump card, she has a visible red spot on her right breast (which you could see earlier even when she was wearing her blazer), gone when she gets up from the floor after the explosion. (02:05:00)
Continuity mistake: In the close-up of Helen igniting the alcohol on the floor, she moves the arm away from the floor and all the way out of frame, appearing also to get up from her kneeling position. A few seconds later in the wider view of the room she is still with her hand down. (02:04:15)
Continuity mistake: When Helen is bashing the bar, the gestures of the other characters in the background are inconsistent from shot to shot (just look at Kate Hudson and Kathryn Hahn's reaction shots, for instance). Same when a few seconds later she throws pillows in the fire. (02:04:00)
Continuity mistake: Helen pleads someone to say "I saw the napkin before he burned it." In the background, Miles is standing, hands down his sides. The camera cuts awa a split second on Claire and Lionel, and then there's a close-up of Edward Norton leaning with the back, and the palms of his hands, against the table. Same few moments later. (02:00:10)
Other mistake: In the original version and in the flashback, Benoit Blanc's delivers the lines about the "loaded gun on the table" in a different way and gestures differently throughout it. (01:56:10)
Plot hole: It's an established fact that the culprit is an idiot (actual quote), but still, not a COMPLETE idiot. Some things such as keeping the envelope as some sort of trophy are in line with the hubris of villains, but there's absolutely no reason at all why he would still have in the back pocket of his pants Duke's phone after having a ton of time to get rid of it (he got rid of the gun and a pair of gloves he had the time to go look for in the dark too), especially in a spot so visible and being known for not owning any phone himself. (01:53:40)
Other mistake: During the first part of the movie, the Mona Lisa shield is triggered by all sorts of acute sound; phone alerts, speaking too loudly. Somehow it is also never released (one wonders how can it detect when the threat is over). At any rate, after the gag has run its course, in the third act the protection is not triggered anymore except when the plot makes it convenient (the lighter). (01:57:40)
Other mistake: In the close-up of the article about Andi's death (the second time we see it, during the denouement, since the first time when Helen sees it the framing is too tight to notice), her full name (Cassandra) is misspelled in the body of the article ("Casandra"). It also mentions her sister Helen; if her identity is so well known and accessible, considering how high profile the trial was, it's borderline insane that nobody would know about her; the media would have been all over her. (01:54:00)
Continuity mistake: When Helen reveals herself holding the envelope on the stairs, she holds it with one, then two hands in the two separate shots. (01:52:00)
Audio problem: The second time we hear everyone reacting to Andi's death, the timing of the lines is different and Edward Norton says "God, Andi." (01:46:00)
Continuity mistake: In the flashback, "Andi" is dead with her right arm on the last step in most shots (as she was the first time we saw the scene) or the one below (like when Blanc is crouching and curses saying "Sh*tballs." (01:45:20)
